Nuclear energy is one of the most efficient sources of energy available. It produces more energy than any other fuel of the same mass or volume. Nuclear energy does not produce any direct air pollution or greenhouse gasses. Nuclear energy comes in two forms: nuclear fission and nuclear fusion. Each has its own advantages and disadvantages and continually become more efficient.
Nuclear energy is an idea that came from the Soviet Union in 1954. By the end of 1989, 428 nuclear power plants were in the world. One hundred-eight of those resided in the United States. Fifteen countries in the world receive at least 30% of their energy from nuclear power. France is the leader, receiving over 77% of their energy from nuclear power plants. Japan follows France with a 33% dependence on nuclear energy, 26% in the United Kingdom, and 20% in the United States. Unfortunately, nuclear power in the United States is declining. The high cost to build a power plant, safety, radioactive waste problems, political/social issues, and other concerns are to blame for the decline in nuclear energy in the United States.
No new nuclear reactors have been ordered or built in the United States in more than a decade. A significant reason for the decline in nuclear energy is the cost to build. When originally introduced, it was believed that nuclear power plants would produce energy “too cheap to meter.” However, over one-hundred of the reactors ordered between 1970 and1980 were cancelled simply because they were too expensive to build. As the facilities become older, equipment must be replaced with safer, more advanced equipment. Reactor vessels-the pot that holds the Uranium- becomes brittle over time because it is constantly being struck by protons and gamma rays. When the brittleness becomes a safety hazard, the vessel must be replaced. Pipelines and sensors must also be replaced, as they are vital to the retention of radioactive material.
Scandals have also been a problem for the nuclear industry. Problems, such as operators falling asleep on shift, forged safety checks, and drug use by guards have plagued the industry in the past. Given the magnitude of a nuclear accident, there must be no toleration for such incidents.
Antinuclear activists have also significantly added to the cost by lobbying to make nuclear power plants too expensive to build. These groups lobby not to make the reactors safer, but to delay the construction of the plants by demanding design changes. They often raise serious issues with the Nuclear Regulatory Commission. At first the NRC silently dismissed these issues, but as public pressure mounted on certain issues they began to endorse some of their concerns. Some of the outcomes were evacuation plans, improved safety features, and improved training of employees. Although there have been some positive outcomes from the activists, their central goal is to prevent nuclear power plants from existing.
Nuclear fission is a process in which a heavy nucleus is split into two lighter nuclei with smaller mass numbers. The nucleus of an atom consists of protons and neutrons. Protons have a positive charge, and neutrons are neutral. After the heavy nucleus splits, the two smaller nuclei lose mass because it becomes energy (approximately 0.1 percent of the original mass is given off as energy according to Einstein’s theory E=mc^2). The nucleus splits when it receives an additional neutron, which gives the nucleus the energy it needs to split. During the reaction, energy and approximately two to three neutrons are given off. These neutrons can produce a chain reaction by striking and splitting another nucleus, and so on, and so on. Among the forms of energy given off during a reaction are kinetic energy from the fission products, gamma rays, and kinetic energy from the neutrons.
A major advantage of nuclear fission is the tremendous amount of energy it produces. One gram of Uranium 235 produces more energy than 2.5 tons of coal or 3,840 gallons of petroleum. A nuclear power plant only needs to burn three kilograms of Uranium 235 a day to supply a city of one million people. One pound of enriched Uranium can power an aircraft carrier longer than one million gallons of gasoline would be able to. This is remarkable, considering a pound of Uranium 235 is smaller than a baseball. If there were no other energy source available in the world, there is currently enough Uranium to supply the world’s energy needs for over 100 years. Canada, Australia, and Niger are currently the largest sources of Uranium. Uranium is a much cheaper source of energy than coal and petroleum products and is environmentally friendly. In the year 2000 alone, nuclear energy made 72% of the worlds’ emission free energy. This is clearly a major advantage of nuclear energy, but with the pros come the cons.
Spent nuclear energy produces waste. Nuclear waste is highly radioactive and extremely dangerous. Radioactivity is the decomposition of a nucleus that produces another, smaller nucleus and high amounts of energy in the form of alpha particles, beta particles, gamma rays, and protons. This release of energy is what is so harmful to living organisms. As the radiation strikes living tissue, it can knock electrons out of their orbit around a given atom. This loss of electrons can cause anything from death, genetic mutations, to cancer. This process of decay takes tens of thousand of years for the nucleus to become stable. One of the largest problems plaguing nuclear industry is the disposal of and/or storage of nuclear waste.
The U.S. Department of Energy is responsible for the disposal of all nuclear waste. The DOE wants to put the spent radioactive material in a glass-like substance to keep it from mixing with the soil and water, and then bury the waste in rock formations deep inside the earth. However, due to antinuclear activists, this plan is on hold. During the cold war, tons of nuclear waste was produced by the military to make nuclear weapons. To solve the disposal problem, the DOE decided to bury the nuclear waste in salt beds located in New Mexico. These salt beds have been stable for over 200 million years and are over 2,000 feet thick. They safely contain and secure the hazardous nuclear waste.
Although a place to secure the radioactive waste produced during the cold war has been established, there is still no safe house for the commercial nuclear waste. As a result, the commercial radioactive waste is being stockpiled at reactor sites around the U.S. The waste is usually stored in special steel containers that are stacked in pools of water close to the reactor. Alternatives to solve the disposal of nuclear waste are to rocket the waste into the sun, bury it deep in the ocean, or encase it in concrete chambers underground.
The major concern of nuclear fission is a nuclear meltdown. A nuclear meltdown is when the nuclear fuel becomes so hot it melts through the metal concrete structures protecting it. It could then reach temperatures of 5,000 degrees F, seep into the ground, and reach the water table. A large amount of radioactive material would also reach the atmosphere, affecting millions of people. Such an incident happened on April 26, 1986, at the Chernobyl power plant in the Soviet Union. Some lab technicians made mistakes that led to two huge steam explosions that blew the roof off the building. This explosion released a cloud of deadly radiation into the air, affecting much of Eastern Europe and the Soviet Union. More than 135,000 people had to be evacuated, and the radiation levels are still so high that nobody can return. This incident gives us the reality of a nuclear accident: it is a high magnitude, low probability event. The effects of a nuclear accident are catastrophic, but the probability that the accident will occur are extremely low. Human error ranks first among the most contributing factors to nuclear accidents, as the scenario in Chernobyl displays. As a result, nuclear companies give their employees extensive training and are always researching better safety measures to establish within the reactor.
Due to the large magnitude of a nuclear accident, several precautions are taken within the design of a nuclear power plant to prevent such an incident. To begin with, enriched Uranium is collected into bundles and submerged into water, which acts as a coolant. Heat is generated as nuclear fission takes place between these “bundles” in the water. As the temperature increases, the water begins to turn into steam and build pressure. This steam pressure is used to turn a turbine, which spins a generator to produce electricity. A nuclear power plant is identical to any other fossil fuel plant. The only difference is the source of energy used to generate steam.
Although the water surrounding the bundles acts as a coolant, it is not enough to keep the enriched Uranium from overheating and melting. To control the flow of neutrons between the bundles, control rods are lowered between them. Control rods are made of special materials that absorb neutrons. To increase the flow of neutrons between bundles (thus creating more heat and electricity), the rods are raised. To decrease the flow, they are simply lowered to prevent the neutrons from colliding and producing energy. The Control Rods are an important safety feature, because they can shut down a nuclear reactor all together simply by lowering them into the bundles in case of an accident or emergency.
In addition to the control rods, the nuclear power plants are designed to prevent any leakage of radioactive material from the plant. This barrier begins with a radiation shield, which absorbs radiation and is housed within a steel containment vessel. This large vessel houses the nuclear reactor and all the hardware required to keep the reactor operational. Finally, the containment vessel is protected by a large concrete building that is strong enough to withstand the impact of a Boeing 747. This three-layered structure is necessary to prevent radioactive material from escaping the power plant in an incident such as Three Mile Island. Chernobyl did not have these structures, which resulted in catastrophe.
Nuclear fission clearly has many advantages as an energy source. However, due to its drawbacks, many scientists believe that fission plants will eventually be replaced by nuclear fusion plants. Nuclear fusion is the energy that powers the sun. Instead of splitting atoms apart, fusion joins two light nuclei together. Nuclear fusion produces much more energy than nuclear fission. Currently, the most feasible way to get a fusion reaction is to use the two heavy isotopes of Hydrogen: Deuterium(D) and Tritium(T). A basic overlook of the reaction is D^2 + T^3 à He^4 + N. As you can see, the initial mass of D^2 + T^3 is greater than the product He^4. The loss of mass is due to the release of a neutron. This exothermic reaction releases an extremely large amount of energy. Another major advantage of nuclear fusion is the fact that it is not radioactive as in the case of nuclear fission. There is also a plentiful supply of light nuclei, because ѕ of the earth is covered with water. Water is the source in which Deuterium is obtained, and it is estimated that the Deuterium supply could last for millions of years. Tritium comes from lithium, the lightest metal found in the earth’s crust. It is estimated that there is enough Lithium to process Tritium for over one thousand years.
Although nuclear fusion appears to be the perfect source of energy, a convenient method to effectively use it has not yet been discovered. Nuclear fission is set off by the addition of a neutral neutron. It takes little or almost no energy to set off the reaction. Nuclear fusion, on the other hand, requires the addition of protons. Since protons have identical positive charges, they repulse each other. Extreme temperatures of up to 4 x 10^7 Kelvin are required to bind the particles together and release binding energy. This is almost identical to the temperature of the sun. Scientists are currently studying efficient methods to make nuclear fusion more feasible. Although there are many complications, many scientists believe it is only a matter of time before nuclear fission is replaced by nuclear fusion.
Although nuclear energy would appear to be the answer to a large energy-crisis, there are obstacles that remain in its success. The general public often does not understand all of the circumstances relating to nuclear energy. To fuel the fire, antinuclear activists portray the nuclear industry as environmentally-insensitive monsters. While some activists are clearly concerned with safety issues, others want to omit the nuclear industry in entirety. Nobody wants a nuclear accident, and to spread propaganda against the industry is only hurting the energy crisis. Environmentalists are often among those most outspoken against the industry. The irony in their argument is the fact that nuclear energy is one of the most environmentally friendly sources of energy available. Yes, there is a large risk dealing with nuclear energy but the probability of such an event occurring is slim to none. Fossil fuels have had more environmental hazards than nuclear power plants. From oil spills in the ocean to burning coal mines, the ecology of the earth has been severely harmed by these current alternatives. Activists are too quick to criticize than to come up with a solution. Fossil fuels are criticized for contributing to the “global warming” theory. The “greenhouse effect” blamed on unregulated industry and transportation polluting our atmosphere. While energy conservation and education are important, it doesn’t solve the long term problem: energy is needed and is increasing in demand as technology and our way of life advances. It is simply not feasible to install a solar panel on every house, or a windmill on every hill.
Fueling the future is a growing challenge for the world. At the current rate of consumption, fossil fuels will soon run out. Nuclear energy is clearly one of the best answers to our energy problems. Nuclear fission and fusion produce a tremendous amount of energy for their mass and are very safe when used properly. New research and developments are continually refining and improving current methods of use. As a result, nuclear power will eventually become one of the world’s largest supplies of energy.